This subclass is to be seen as an application place in relation to the function-oriented aspects covered by F23B, Combustion apparatus using only solid fuel, and F23C, Combustion apparatus using fluent fuel).

of general interest for combustion of different types of solid or fluent fuel, for example not specially adapted for a particular fuel, or

specially adapted for fuels other than those provided for in this subclass, for example "normal" commercial fuels, such as oil, natural gas, coal, firewood, wood chips, wood pellets or straw.

If methods or apparatus covered by this subclass are also of general interest for combustion of "normal" commercial fuels classification should also be made in other subclasses of F23. The decision on whether an apparatus is specially adapted or not is sometimes not easy to decide. In doubtful situations classification should therefore always be made in both this subclass and other subclasses of F23.

Subclasses F23D and F23H - F23Q are to be seen as general detail places in relation to this subclass. Classification of details of apparatus in this subclass should be restricted to inventions that are clearly specially adapted for methods or apparatus that are covered by the subclass. If a detail of an apparatus is specifically covered in a group of F23D or F23H - F23Q, classification should be made in that group and not in this subclass.

Relationship between this subclass and other application places

Combustion is often used for purpose of heating or performing different operations. This subclass is therefore related to many places providing for uses of heat. In many of these fields the combustion apparatus can be considered a detail of a bigger entity. A non-exhaustive list of examples of such classes or subclasses will be found under the heading "Informative references".

Relationship between this subclass and places for gasification or destructive distillation

C10B covers destructive distillation of carbonaceous material for production of gas, coke, tar or similar matter.

Classification is made in these places if the combustible substances produced, e.g. gas or coke, are burned in an apparatus separate from the gasification or distillation apparatus.

Classification is made in this subclass if complete combustion takes place in the same apparatus as the gasification, for example in different parts of the same combustion chamber or in an afterburner immediately connected to a primary combustion chamber.

These subclasses only cover matter that is not completely covered by this subclass. Examples of such matter are processes that include a combustion step in combination with other steps that together form a process for disposal of waste or reclamation of contaminated soil.

In this subclass/group, the following terms (or expressions) are used with the meaning indicated:

Air

a mixture of gases containing free oxygen and able to promote or support combustion

Primary air

air supplied to the burning fuel in order to liberate combustible gases

Secondary air

air supplied to the combustible gases liberated by the primary air in order to complete their combustion. The expression "secondary air" covers "tertiary air" etc.

Burner

a device by which fluid fuel or solid fuel suspende in air is passed to a combustion space where it burns to produce a self-supporting flame. A burner includes means for feeding air that are arranged in immediate connection with a fuel feeding conduit, for example concentric with it.

Combustion

the direct combination of oxygen gas, e.g. in air, and a burnable substance

Combustion chamber

a chamber in which fuel is burned to establish a self-supporting fire or flame and which surrounds that fire or flame

Combustion zone

the part of a combustion apparatus where the reaction takes place between air and fuel

Fuel

any combustible material that can be burned, regardless of whether the main purpose of burning it is for releasing energy therefrom or for disposing of it or rendering it less harmful

Waste

an undesired material that can be consumed by combustion for the primary purpose of disposing of it or rendering it less harmful, and not solely for releasing energy therefrom

Synonyms and Keywords

In patent documents the following abbreviations are often used:

CFB

Circulating fluidised bed

EHC

Electrically heated catalyst

FBN

Fuel-bound nitrogen

HC

Hydrocarbons

NOx

Nitrous oxides

PFBC

Pressurised fluidised bed combustion

SOx

Sulfur oxides

UHC

Unburned hydrocarbons

In patent documents the expression "boiler" is often used with the meaning "combustion apparatus".

In patent documents the expression "burner" is often used with the meaning "combustion apparatus".

This subgroup is supposed to be used in all cases where the entire plant is described or just sketched, even though those components of the plant which are not part of the invention are already well known and described in general terms only.

Special rules of classification within this group

Double classification normally applies in this subgroup.

When classifying in this subgroup, add also the relevant Indexing Codes from the range F23J 2215/00-F23J 2219/80 for all the components of the fumes purification section, even if they are not part of the invention.